1. Field of the Invention
The present invention relates to a four massaging head type massaging mechanism for massaging a user's body with four massaging heads which are independent of each other, and massaging apparatus incorporating the massaging mechanism.
2. Description of the Related Art
Massaging apparatus in which a four massaging head type massaging mechanism for massaging a user's body with four independent massaging heads is installed in a backrest is known particularly in the technical field of chair type massaging apparatus. The massaging mechanism concerned has a rotary shaft supported in the right-and-left direction, a pair of right and left swing arms which are interlockingly linked to the rotary shaft so that one ends and the other ends of the swing arms corresponding in the right-and-left direction to each other are moved in the opposite directions in the right-and-left direction in conformity with the rotation of the rotary shaft, and a massaging head which is secured to each of one end portion and the other end portion of each swing arm (see Japanese Unexamined Patent Publication No. 2000-237257, for example).
A pair of right and left cam members having cam faces which are inclined in the opposite directions with respect to the rotary shaft are fixed to the rotary shaft. A radially outwardly projecting lever is secured to each cam member so as to be relatively rotatable with respect to the cam member, and a center portion of each swing arm is rotatably linked to the tip of the lever, so that each swing arm is swung in the right and left direction through the lever by the cam function of the cam member fixed to the rotary shaft.
Accordingly, the massaging heads on one end portion side of the swing arms (and the massaging heads on the other end portion side of the swing arms) are approached to and separated from each other to thereby carry out a massaging operation.
The above massaging mechanism further includes a rotary shaft for tapping operation disposed in parallel to the rotary shaft. The rotary shaft for tapping operation is provided with a crank member having a shaft portion eccentric with respect to an axis of the rotary shaft, and one end portion of a crank rod is pivotally secured to the crank member while the other end of the crank rod is pivotally secured to the lever.
When the rotary shaft for tapping operation is rotated, the crank rod is pressed and pulled through the crank member, whereby the lever is reciprocatingly moved about the rotary shaft. The reciprocating motions of the levers cause the massaging heads to carry out the tapping operation through the swing arms.
Since a back of a user's body is normally curved substantially in the S-shape from the lower side of the neck to the waist, the swing arm of the massaging mechanism described above is rotatably linked to the tip of the lever to rotate the swing arm in conformity with the S-shaped curve of the user's back, so that all the massaging heads can be substantially uniformly abutted to the back. Accordingly, the massaging operation using all the massaging heads can be efficiently performed.
However, this massaging apparatus has a disadvantage that the whole thickness of the massaging mechanism (the depth in the front-and-back direction) is increased by an amount corresponding to the lever because the massaging apparatus is provided with the lever projecting from the rotary shaft toward a front surface side of the backrest.
A large thickness of the massaging mechanism requires a broad space in the backrest for housing the massaging mechanism, and thus the thickness of the backrest must be increased to secure the space. Since this results in an increase in size and weight of the chair type massaging apparatus, an overall balance of the chair (the relative balance to the seat portion) is lost, and the appearance of the chair may be degraded.
Examples of conventional massaging apparatus further include a stationary massaging apparatus to be placed on a floor for use, and had-carriable massaging apparatus capable of being carried by hands in addition to the chair type massaging apparatus. In those examples, the large thickness of the massaging mechanism induces increase in size and weight of the overall massaging apparatus, resulting in an obstacle to portability.
In order to overcome the above disadvantage, the thickness of the massaging mechanism may be reduced by omitting the lever, i.e., securing the swing arm to the rotary shaft while directly coupling the crank rod to the swing arm. In this case, however, the rotation of the swing arm about the rotary shaft is restrained by the crank rod, thereby hindering all the massaging heads from uniformly contacting a user's back in conformity with the S-shaped curve of the back. Therefore, since some of the massaging heads cannot contact the user's body at all times or the kneading or tapping force is partially weakened, effective massaging operation cannot be performed.